24 Hour Fish Tank Cycling: It’s Possible, But Is It Worth It?

One of the most irritating aspects of setting up a brand-new fish tank is the cycling process. This is not due to the difficulty of the task at hand. The problem is the extremely long time required to cycle your tank, which can even take up to two months!

Luckily there’s a quicker way to cycle your tank. It’s so quick it can bring months of waiting down to a day. However, bringing a two-month process down to a single day has its benefits and drawbacks, but it is not an easy task. In this article, we’ll discuss how to cycle a tank in a single day.

What Does It Mean ‘Cycle A Fish Tank’?

Cycling your new aquarium is the initial and most important step in making a healthy environment in your fish tank so fish and plants can live and grow. It actually isn’t hard, but doing it may really take a while, and it can be done in a few different ways.

Cycling is the process of letting a living population of beneficial bacteria establish a colony in an aquarium. These bacteria live on the filter media, gravel, and other surfaces inside the aquarium. As they go about their normal lives, they filter the water naturally by converting harmful ammonia into nitrite and then into less harmful nitrates.

Before adding animals to an aquarium, the bacterial colonies, which are found in the biofilter, should be well-established. Fish and other organic materials release ammonia in the tank, which the bacteria is meant to break down. If they aren’t, it’s unlikely that the animals inside the fish tank will survive. 

What Are The Methods To Cycle A Fish Tank?

Bacteria that break down organic waste are important for any environment with living things, and there are lots of them in nature. But if you just set up your brand new aquarium, there won’t be any bacteria in there. Here are a few methods for introducing nitrogen-fixing bacteria to your aquarium and getting the nitrogen cycle rolling.

1. Fish-Less-Cycle

Most aquarists would suggest using the fish-less cycle method, in which the aquarium water cycle is done naturally. We have to allow time for the beneficial bacteria to grow on their own, just slowly dropping fish food for ammonia. Over time, the amount of ammonia goes down until it is completely broken down into nitrates.

2. Fish-In-Cycle

Fish-In-Cycle is a method that you should only use if you know a lot about cycling and have done it before. This method gets ammonia from the waste and urine of living fish, which is not a good idea because fish are always at risk. During the process, the levels of ammonia and nitrate are prone to changes, and there are possibilities that your fish can die or get hurt.

3. Instant Cycle

An instant cycle is a cycle that is completed after a day. But you shouldn’t really do this unless you have an emergency and need to set up a fish tank right away. This is done by taking things from another fish tank that probably have colonies of good bacteria and putting them in yours so you don’t have to wait for so long.

Steps To Instant Cycle: How To Cycle A Tank In 24 Hours

Fish tank cycling is the process of establishing a new biological cycle in your aquarium, which typically takes a couple of months to complete. Yet there are times when we’ll have to start a brand new tank from scratch and let it cycle in just one day. If you want to know how to instantly cycle your tank, look no further than this detailed guide.

1. Prepare The Tank

When you want to cycle a tank instantly, you should already have everything you need. Put things like treated water, gravel, decors, heater, and other accessories in the fish tank. You should also install an air pump because highly oxygenated water makes it easier for good bacteria to grow and multiply.

2. Add A Used, Cycled Filter

The next step is to obtain a filter from another functioning aquarium that has already been cycled. This is where we were gonna get the beneficial bacteria to help kickstart the cycle in your new aquarium. The cycled filter may look old and gross, but you refrain from cleaning it.

3. Add a Used, Cycled Gravel

Gravel is a good place for good bacteria to live in a fish tank that has been cycled. Next, add a single cup of used gravel and mix it in with the gravel you already have. If your tank is bigger than 20 gallons, you can add an additional cup of gravel.

4. Add Rotten Fish Food

It might look gross and dirty, but it’s actually necessary for cycling your tank. The rotten fish food is for adding organic matter to your tank that will turn into ammonia. The good bacteria in your fish tank will need ammonia to eat.

5. Add A Bottled Bacteria

Beneficial bacteria in a bottle can help to cycle a tank quickly. Most of the time, these are called “aquarium bacteria starters,” and there are a few companies that produce bottles with real beneficial bacteria in them. Make sure to check that the product hasn’t passed its expiration date, as bacteria may die in older bottles.

6. Wait And Observe Ammonia And Nitrates

After doing the steps above, wait for 24 hours and use a test kit to keep an eye on the amount of ammonia in your fish tank to see whether it is staying the same or going down. If ammonia levels go down and nitrate levels go up, that means the nitrogen cycle is working right. Once the ammonia has been nitrified, you can also add aquatic plants to help remove nitrates and get more oxygen into the water.

7. Add Fish

If the ammonia and nitrite levels are both 0 and the nitrate levels are below 20 ppm, you can start putting the fish in the tank. If you can, add some hardy fish and make sure that you do not overstock to prevent a sudden increase of ammonia. The recommended is one fish per 10 gallons.

Is Cycling A Fish Tank In 24 Hours Recommended?

There are a number of scenarios in which knowing how to cycle an aquarium in a day could prove useful. Maybe you need to have your aquarium up and running quickly because of an emergency. Or perhaps you just bought and set up a new tank without buying or adding a cycling agent.

The good news for us aquarists is that you can cycle the aquarium in a single day. But just because you can doesn’t mean you should, especially if it’s a new tank. The standard cycle should take anywhere from 10 to 14 days, or even longer before it’s ready for fish.

Learning how to quickly cycle an aquarium is a useful skill to have as an aquarist. But a regular cycle that lasts a few weeks is always safer for your fish and creates a far better balance. This way, we can guarantee that our fish have a safe place to live in.

When Should You Cycle a Fish Tank in 24 Hours

Cycling a tank is important and necessary if you want to keep fish. Most of the time, this will take you weeks or months, but there may be times when you need to do it in one day. Here are a few reasons why you might need to cycle a fish tank in one day.

1. Major Contamination

There are times when you might have an emergency and spill a lot of dangerous chemicals into your aquarium tank. When this happens, you might need to do a partial water change to dilute the chemical and clean the water. You could also throw out all of the water and set up and run a new one in 24 hours.

2. Complete Water Change

You just started adding fish to your new fish tank, but the ammonia levels are already through the roof. What you may need to do is reset your tank and start a new cycle, which can be done in just 24 hours.

3. Unstable Water pH

Your water pH may not be stable because waste is building up in a way that can’t be stopped. When this happens, you might wanna redo your tank and do another cycle that can be done in 24 hours. Waste is supposed to be broken down by healthy bacteria, which will stop the alkaline levels from going up.

4. Parasitic Outbreak

Parasitic outbreaks are hard to deal with and may require you to move your fish to a separate tank so they can be treated. But if you don’t have a fish tank to move your fish to, you might need to cycle a new tank for at least 24 hours.

5. Sudden Need for Unprepped Quarantine Tank

You might need to set up a quarantine tank at certain times or in certain situations. You might want to watch your fish or just move everything to a different fish tank so you can clean your main fish tank thoroughly. When these things happen, you can set up a tank and let it cycle in one day.

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Can You Add Fish to A Fish Tank After 24 Hours?

You shouldn’t add fish to a tank for at least 24 hours to allow the tank to “cycle” and the nitrifying bacteria to establish themselves sufficiently to break down any ammonia your fish makes. But that’s only the case if you’ve ever tried to “quick-cycle” your aquarium with bottled bacteria.

How Long Should You Let Your Tank Cycle Before Adding Fish?

If you’re using a natural, old-fashioned filter sponge to cycle your tank, wait 2 to 4 weeks before introducing fish. Before you put the fish in the tank, test the water to see if the ammonia and nitrite levels are 0 ppm, and the nitrate levels are below 20 ppm.

How Long Does Cycling a Fish Tank Normally Take

The cycling process typically takes between six and eight weeks. After about that time, the levels of ammonia and nitrite should be good enough, and you can begin to add the fish to the tank.


Cycling a fish tank is an important part of fish keeping. There are many ways to do it, but it all comes down to getting an established colony of good bacteria in your aquarium. These bacteria are important because they break down the ammonia in your fish tank, making it a good place for your fish to live. Cycling a tank can take weeks or months, but it can also be done in a day, though this doesn’t guarantee that it will work and is hard to do. The most important thing, though, is to keep harmful ammonia and nitrate levels low to keep your fish happy and healthy.

About the author

Hey there! I'm Antonio, the passionate owner and chief editor of Betta Care Fish Guide. With over half a decade of hands-on experience, I've become your go-to expert for all things betta and tropical fish.

Over the past 5 years, I've not only kept bettas and other tropical fish but also connected with a diverse network of hobbyists, seasoned fishkeepers, and even veterinarians.

Now, I want to help other beginner fish keepers who had the same questions as me when they were just starting out! So they can save themselves a ton of time and keep their fish happy and healthy!